memo.lua

local f = GetInventoryCount
local memo = setmetatable({}, {
	__index = function(t,i)
		-- Get the value and stash it for later
		local v = f(i)
		t[i] = v
		return v
	end
})

-- This calls the function
local x = memo[123]

-- This pulls the value from the table
-- thus saving a function call
local y = memo[123]